Monopulse switching system

ABSTRACT

6. An electronic lobe switching system for locating a target in space comprising: a simultaneous lobing antenna including four symmetrically positioned radiators defining the corners of a square, and a plurality of intercoupled hybrid junctions having four input terminals, a sum output terminal, an azimuth output terminal and an elevation output terminal, each of said radiators being coupled to one of said input terminals and adapted to excite a microwave signal therein representative of a microwave signal received from said target, said plurality of hybrid junctions being adapted to develop a sum signal in said sum terminal, an azimuth signal in said azimuth terminal and an elevation signal in said elevation terminal representative of the range, the azimuth and the elevation of said target respectively; a receiver responsive to a microwave error signal and a reference signal and adapted to develop demodulated error voltages representative of the azimuth and elevation of said target; and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal and coupling and said simultaneous lobing antenna to said receiver, said switching circuit being adapted to develop said microwave error signal and including a microwave two-channel switch, a microwave phase inverter, adder means, and an electronic reference generator for developing said reference signal and first and second control signals, said switch being coupled to said phase inverter and to said generator and responsive to said first control signal for sequentially applying either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being coupled to said generator and being responsive to said second control signal for sequentially introducing a 180* phase shift to the sequentially applied azimuth or elevation signal, and adder means coupling said phase inverter to said sum terminal and being adapted to mix the sequentially phase-inverted signal from said phase inverter and said sum signal to develop said microwave error signal.

United States Patent [191 Kreinheder MONOPULSE SWITCHING SYSTEM [75]Inventor: Donald E. Kreinheder, Los Angeles, Calif.

[73] Assignee: Hughes Aircraft Company, Culver City, Calif.

[22 Filed: May 1, 1957 [21] Appl. No.: 658,915

Primary Examiner-Malcolm F. Hubler Attorney-James K. Haskell and EarnestF. Oberhcim EXEMPLARY CLAIM 6. An electronic lobe switching system forlocating a target in space comprising: a simultaneous lobing antennaincluding four symmetrically positioned radiators defining the comers ofa square, and a plurality of intercoupled hybrid junctions having fourinput terminals, a sum output terminal, an azimuth output terminal andan elevation output terminal, each of said Jan. 9, 1973 radiators beingcoupled to one of said input terminals and adapted to excite a microwavesignal therein representative of a microwave signal received from saidtarget, said plurality of hybrid junctions being adapted to develop asum signal in said sum terminal, an azimuth signal in said azimuthterminal and an elevation signal in said elevation terminalrepresentative of the range, the azimuth and the elevation of saidtarget respectively; a receiver responsive to a microwave error signaland a reference signal and adapted to develop demodulated error voltagesrepresentative of the azimuth and elevation of said target; and aswitching circuit responsive to said sum signal, said azimuth signal andsaid elevation signal and coupling and said simultaneous lobing antennato said receiver, said switching circuit being adapted to develop saidmicrowave error signal and including a microwave two-channel switch, amicrowave phase inverter, adder means, and an electronic referencegenerator for developing said reference signal and first and secondcontrol signals, said switch being coupled to said phase inverter and tosaid generator and responsive to said first control signal forsequentially applying either said azimuth signal or said elevationsignal to said phase inverter, said phase inverter being coupled to saidgenerator and being responsive to said second control signal forsequentially introducing a 180 phase shift to the sequentially appliedazimuth or elevation signal, and adder means coupling said phaseinverter to said sum terminal and being adapted to mix the sequentiallyphase-inverted signal from said phase inverter and said sum signal todevelop said microwave error signal.

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SHEET 1 BF 2 law/- PATENTEDJAH 9 ma 3.710.390

SHEET 2 OF 2 92 flax/.4454 v MONOPULSE SWITCHING SYSTEM This inventionrelates to tracking systems, and more particularly, to an electroniclobe switching means for and a method of intercoupling a simultaneouslobing antenna and a single channel microwave receiver to provide a waveenergy tracking system.

Simultaneous lobing systems of the prior art for tracking a targetutilize a single stationary wave energy beam for illuminating the targetwhich, upon reflection, provides an echo signal from which the desiredposition information of the target may be abstracted. The antenna ofsuch a system, which is designated as a simultaneous lobing antennaincludes four symmetrically spaced radiator elements which are equallyexcited by the transmitter of the system to provide the illuminatingbeam. These four radiator elements are also coupled to the receivers ofthe system and are excited by the echo signal to provide information ofthe target location. The four signals developed by the four radiatorsare mixed in a phase and amplitude sensitive hybrid junction means,usually comprising three or four hybrid junctions to developsimultaneous lobing antenna output signals designated as the sum signal,azimuth signal, and the eleyation signal.

The relative amplitudes and phases of the waves excited in the radiatorsby the echo signal are proportional to the angular position of thetarget in a plane perpendicular to the axis of symmetry of the fourradiator elements. By comparing the relative amplitudes and phases ofthe waves in the four radiators with one another, two space quadraturedifference signals designated herein as the azimuth signal and theelevation signal may be developed which give the angular position of thetarget in terms of rectangular coordinates.

In practice, this position information is utilized to maintain thesymmetry axis in coincidence with the line of sight in much the samemanner as used in conical scan tracking techniques by using a feedbacksystem including a torquer system to move and constantly maintain theantenna axis in coincidence with the line of sight.

In a monopulse system, which most commonly employs a simultaneous lobingantenna and which, for the purpose of this specification, is defined asa system capable of providing complete position 'data upon transmissionof a single pulse, the three output signals received from thesimultaneous lobing antenna are fed to three different microwavereceivers for demodulation. The output of each receiver is combined andits phase detected to obtain complete position information.

The desirable major characteristics of a tracking system are completeabsence of moving parts in the antenna, electrical simplicity of thereceiver system and ability to provide complete positional targetinformation in a short time interval. The conventional monopulsetracking system hereabove described requires three microwave receiverswhich introduce great electrical complexity and require additional spacein an otherwise desirable tracking system.

It is therefore an object of this invention to provide a wave energytracking system incorporating the advantages of the monopulse trackingsystem whileat the same time requiring but a single microwave receiver.

It is a further object of this invention to provide a wave energytracking system which provides complete position information of a targetby means of four consecutive pulses and which requires but a singlemicrowave receiver.

It is a still further object of this invention to provide a new methodfor tracking targets in space incorporating simultaneous lobing antennatechniques and electroni cally intermixing the antenna output signals todevelop a single microwave error signal.

It is a still further object of this invention to provide a method oftracking targets in space which is simple and reliable in operations andwhich substantially decreases the complexity attendant in conventionalmonopulse tracking systems.

In accordance with one embodiment of this invention a conventionalsimultaneous lobing antenna is utilized which provides three outputsignals respectively designated as sum, azimuth, and elevation outputsignals. Instead of providing a microwave receiver for each of theseoutput signals the output signals themselves are combined to provide asingle microwave error signal. The intermixing of the signals isundertaken in much the same way as a carrier is modulated byinformation. More particularly, the sum signal furnishes a convenientpulsed carrier and the azimuth signal and the elevation signal areselectively added to or subtracted from the sum signal. This selectivecombination takes place in accordance with a predetermined scheme suchas may be provided by a pro gramming unit.

The sum signal, after having impressed upon it the azimuth and theelevation signals, is designated as the microwave error signal. Themmicrowave error signal which includes complete position. information ofthe target is then demodulated in a. single receiver. A reference signalfrom the programming unit is then utilized for detecting the phase ofthe demodulated microwave error signal in accordance with the priormodulation. Upon phase detecting, error voltages representative of theazimuth and the elevation of the target are obtained.

The novel features which are believed to be characteristic of theinvention, both as to its organization and method of operation, togetherwith further objects and advantages thereof, will be better understoodfrom the following description considered in connection with theaccompanying drawings in which several embodiments. of the invention areillustrated by way of example. It is to be expressly understood,however, that the drawings are for the purpose of illustration anddescription only, and are not intended as a definition of the limits ofthe invention.

FIG. l is a schematic block diagram of the wave energy tracking systemin accordance with this invention;

FIG. 2 is an illustrative diagram showing the geomet rical position of atarget with respect to the simultaneous lobing planes;

FIG. 3 is a schematic block diagram of an embodiment of the electronicreference generator included in the system of FIG. 1; and

FIG. 4 is an illustrative diagram showing the correspondence betweendesignated signals on a time-amplitude basis.

Referring now to the drawings wherein like reference charactersdesignate like parts and particularly to FIG. 1 there is shownschematically a conventional simultaneous lobingantenna coupled to aswitching circuit which switching circuit is an important factor of thisinvention. The simultaneous lobing antenna 10 includes four radiatorsll, l2, l3 and 14 which are symmetrically positioned within a parabolicreflector schematically indicated by a dotted line 16 and usually occupythe corners of a square. The simultaneous lobing antenna 10 alsoincludes a hybrid junction means made up of three hybrid junctions 18,20and 22 and a T- junction 24. It is self evident to those skilled inthe art that a fourth hybrid junction may be substituted for theT-junction wherein the difference branch arm is terminated in a matchedload.

The pair of radiators 11 and 12 are directly coupled to the symmetrybranch arms 26 and 28 of hybrid junction 18 and the pair of radiators 13and 14 are coupled to the symmetry branch arms 30 and 32 of hybridjunction 20. The radiators 11 14 may be dipoles, waveguide horns, orslots. The sum branch arm 34 of hybrid junction 18 and the sum brancharm 36 of hybrid junction 20 are each coupled to a different symmetrybranch arm of hybrid junction 24. The difference branch arm 38 of hybridjunction 18 and difference branch arm 40 of hybrid junction 20 are eachcoupled to a different terminal of the T-junction 24. In this manner,the hybrid junction means is adapted to provide vector addition andsubtraction of the wave energy excited by the radiators between allradiators taken in pairs.

The simultaneous lobing antenna 10 has three output terminals which arerespectively designated as the sum output terminal 42, the azimuthoutput terminal 44 and the elevation output terminal 46 and which arerespectively the sum and difference branch arm of hybrid junction 22 andthe leg of the T-junction 24.

The azimuth terminal 44 and the elevation terminal 46 are both coupledto a two-channel microwave switch 50, the operation of which iscontrolled by a first control signal. In contradistinction to microwavesignals, the control signal is an electrical signal whose frequency isin the range of IO to 10,000 cycles per second. The switch 50 operateslike a single-pole, double-throw switch and in accordance with thecontrol signal impresses either the signal from the elevation terminal46 or the signal from the azimuth terminal 44, but not both, to theoutput terminal 52. Such microwave switches are well known in the art.By way of example, a ferrite microwave switch is described in detail in,High Speed Ferrite Microwave Switches, by George S. Uebele, published inthe IRE Convention Record, 1957 National Convention, Part 1, Pages227-234. v

The output terminal 52 of the switch 50 is coupled to a phase inverter54, the operation of which is likewise controlled by a second controlsignal. This second control signal is similar in character to the firstcontrol signal but has a frequency which differs therefrom as will beexplained in detail below. The function of the phase inverter 54 is topermit propagation of the signal from the switch 52 therethrough either,with or without subjecting the signal to a 180 phase shift as determinedby the second control signal.

The output terminal 56 of the phase inverter 54 is coupled to the sumterminal 42 by means of an intercoupling network 60 which may be avestigial Y-junction well known to those skilled in the art. A microwavegas discharge device 58 which may be a conventional TR tube is providedin the leg of the Y-junction 60 which upon being fired will preventmicrowave energy traversing junction 60 from passing to the phaseinverter 54.

An electronic reference generator 64 which provides the first and thesecond control signal is coupled to the switch 50 and the phase inverter52 as shown. The electronic reference generator also provides areference signal which, as will be explained later, is used in theprocess of phase detecting the error voltages.

The combination of the two-channel switch 50, the phase inverter 54, theintercoupling network 60 and the electronic reference generator 64 isreferred to as the switching circuit which intercouples the simultaneouslobing antenna 10 with a microwave transceiver 66. The transceiver 66 isa conventional microwave receiver and transmitter combination such as isused with conical scan wave energy tracking systems. The switchingcircuit has a single microwave output terminal 62 which is coupled tothe receiver 66 and a single electrical output for a reference signalwhich is coupled to the phase detector portion of the receiver 66.

FIG. 2 shows the position of an assumed target 72 and its associatedgeometry when sighting along the symmetry axis 70 extending through theplane of the paper of the simultaneous lobing antenna 10. The target 72is located above the azimuth plane 74 and to the right of the elevationplane 76. For the assumed target position the azimuth error of thetarget is approximately twice as large as the elevation error. It isfurther assumed that the radiators which occupy positions on linesmaking a 45 degree angle with the two planes 74 and 76 are so spacedthat both the azimuth signal and the elevation signal are positive. Thedesignation of a signal as positive denotes that the phase thereofis thesame as the phase of the sum signal. In other words, the quadrant inwhich target 72 is located provides positive or in-phase error pulsesfor both the azimuth and the elevation signal.

The electronic reference generator 64 of FIG. 1 is shown in greaterdetail in FIG. 3 and includes as its basic component a master oscillator80. The oscillator 80 provides a sinusoidal output signal 82 which, aswill be explained later on, is impressed on the receiver 66 for thepurpose of phase detection. The oscillator 80 is also coupled to anamplifier and limiter 84 which converts the sinusoidal output signal 82into a square wave 86 having the fundamental frequency of the oscillator80. The square wave 86 is the second control signal and is applied tothe phase inverter 54 of FIG; 1 to control the operation of the phaseinverter 54.

The oscillator is also coupled to another amplifier and limiter 88through a frequency doubler90. The frequency doubler 90 doubles thefrequency of the sinusoidal output signal 82 to provide sine wave 91.The amplifier and limiter 88 converts the sine wave 91 into a secondsquare wave 92 having a fundamental frequency of twice that of thefundamental frequency of the oscillator 80. The square wave'92 is thefirst control signal and is impressed on the switch 50 of FIG. 1 tocontrol the single-pole double-throw switch.

The operation of the wave energy tracking system of this invention willnow be explained with the aid of FIG. 4. A transmitter incorporated inthe receiver 66 supplies pulsed microwave energy commonly referred to asthe main bang or the main transmitted pulse to output terminal 62 of theswitching circuit of FIG. 1. The main bang passes through the Y-junction60 and fires the gas discharge device 58 thereby creating a shortcircuit at that coupling junction. If the gas discharge device is aconventional TR tube its location will be an integer number of halfwavelengths from the junction point. The main bang then passes to thesum branch arm 42 of hybrid junction 22 wherein it is equally dividedinto two portions and transmitted by the associated symmetry branch armsthereof to the sum branch 34 and 36 of hybrid junctions l8 andrespectively. Hybrid junctions 18 and 20 further divide the main banginto equal portions and deliver one quarter of the wave energy of themain bang to each of the radiators 11, 12, 13 and 14. The radiators soexcited illuminate the target by generating a single beam whose axis iscoincident with the axis of symmetry of the system. Actually theradiators give rise to four separate beams but for the purpose ofdiscussing the illumination of the target the four beams may beconsidered as a single illuminating beam. FIG. 4 shows four successivemain bang pulses, 100, 101, 102 and 103.

The target reflects a portion of the illuminated wave energy whichreflected wave again excites the radiators 11, 12, 13 and 14. If thetarget is located at a point not lying on the symmetry axis of theantenna system such as the assumed target 72 in FIG. 2, the excitationsof the individual radiators will be out of phase. In fact, this phasedifference in the excitation of the individual radiators provides thepositional information of the location ofthe target.

The wave energy excited by means of the radiators 11 and 12 within thesymmetry branch arms of the hybrid junctions 18 are vectorially addedand subtracted therewithin so that the sum terminal 34 and thedifference terminal 38 provide the respective vector sum and the vectordifference. Similarly, the wave energy excited by means of the radiators13 and 14 within the symmetry branch arms of the hybrid junction 20 arevectorially added and subtracted therewithin so that the sum terminal 36and the difference terminal 40 provide respectively the vector sum andthe vector difference.

The vector sums, respectively, of radiators 11 and 12 and radiators 13and 14 are further vectorially added and subtracted in hybrid junction22 from which is derived the vector sum of radiators 11 to 14 to providethe sum signal in sum terminal 42 and the vector difference providingthe azimuth signal in azimuth terminal 44. In a similar fashion, theT-junction 24 provides the sum of the phase difference between radiators11 and 12 and radiators l3 and 14, which sum gives rise to the elevationsignal in the elevation terminal 46.

FIG. 4 shows four consecutive pulses 104, 105, 106 and 107 of the sumsignal. The time displacement t between the pulse 100 of the main bangand the pulse 104 of the sum signal provides an indication of the rangeof the target, t being the time it takes the wave energy to travel twicethe distance from the simultaneous lobin g antenna to the target.

The azimuth signal shown in FIG. 4 comprises the pulses 108, 109, 110and 111. The relative magnitude of the pulses is a direct indication ofthe azimuth angle of the target. The elevation signal also shown in FIG.4 is designated by pulses 112, 113, 114 and 115. The relative amplitudeof the elevation pulse 112 is approximately twice the amplitude of theazimuth pulses 108 which is an indication that the elevation angle istwice as great as the azimuth angle. These relative magnitudes are inaccord with the position of the target 72 in FIG. 2.

The above three signals, namely the sum, azimuth and elevation signalsare the output signals of the conventional simultaneous lobing antenna.Mixing of these signals is accomplished by the switching circuit of thisinvention which, by combining these signals, derives a single microwavesignal.

The fundamental frequency of the master oscillator of the electronicreference generator of FIG. 3 is one-quarter of the pulse repetitionrate of the trans mitter incorporated into transceiver 66 whichoriginates the main bang. Hence, there are four main bang pulses to onecycle of the oscillator 80.

The microwave switch 50 of F IG. 1 is actuated by the control signal 92of FIG. 3 having a frequency twice that of the oscillator. Since theswitch is brought to the same position every second pulse, the switchwill alternately pass an azimuth signal pulse and an elevation signalpulse to the phase inverter. This is illustrated diagrammatically inFIG. 4 where the output from the switch consists of azimuth signal pulse108 followed by elevation signal pulse 113 which again is followed byazimuth signal pulse 110 and elevation signal pulse 115.

The pulse inverter 54 of FIG. 1 is actuated by the square wave signal 86of FIG. 3 which has the same frequency as the oscillator and which willactuate the phase shifter twice during each oscillator cycle. In otherwords, the phase inverter 54 will let two pulse signals pass throughwithout changing the phase and thereafter invert the phase of the nexttwo pulses. In accordance with the designation of the term positive orin-phase, the inverted phase pulse will be negative. This can be seendiagrammatically in FIG. 4 where pulse 108 and pulse 113 from the switch50 are permitted to pass freely through the phase inverter whereas pulse110' and 115' have suffered a 180 phase shift with respect to the pulsesfrom the switch 50.

The output of the phase inverter is then combined with the sum signal inthe Y-junction 60. The result of this combination is showndiagrammatically in FIG. 4 where pulse 116 is a combination or additionof pulse 104 and 108, pulse 117 is a combination of pulse 105 and 113,pulse 118 is a combination of pulse 106 and 110, and pulse 119 is acombination of pulse 107 and l 15'. The pulses l 16, 1 17, 118 and 119provide the single microwave error signal having; an envelope 120 whichis the error envelope from which error voltages representative of theazimuth and elevation may be obtained by conventional demodulationtaking place within the transceiver 66.

More particularly, the microwave error signal of FIG. 4 whose envelope120 has the same frequency as the reference signal 82 of FIG. 3 isapplied to the standard microwave receiver incorporated into transceiver66 which has a mixing stage, an IF stage, and which demodulates themicrowave error signal to abstract therefrom the envelope 120.Thereafter, the envelope 120 is phase detected by means of the referencesignal 82 by standard conical scan tracking methods as are well known tothose skilled in the art.

There has been described a method and a means of utilizing aconventional simultaneous lobing antenna and combining the output ofthis antenna in such a way as to obtain a single microwave error signalwhich has modulated upon it information representative of the azimuth,the elevation and the range of the target. The switching means used inderiving the microwave error signal employs a microwave switch and amicrowave phase inverter both of which are only required to handle verysmall amounts of wave energy power and which therefore can be veryefficiently operated. The advantages which the wave energy trackingsystem of this invention provide are the use of a simultaneous lobingantenna system having no moving parts and therefore greater mechanicalsimplicity and a single microwave receiver as used in conical scanningtechniques with a resultant saving of weight and space.

What is claimed as new is:

1. In an electronic lobe switching system for locating a target in spaceand including a monopulse antenna having three output terminals whichprovide respectively a sum signal, an azimuth signal and an elevationsignal, a receiver responsive to a microwave error signal and areference signal and adapted to develop corresponding demodulated errorvoltages therefrom,

and a switching circuit responsive to said sum signal, said azimuthsignal and said elevation signal and adapted to develop therefrom saidmicrowave error signal, said switching circuit coupling said monopulseantenna to said receiver and comprising: a phase inverter; a microwavetwo-channel switch coupled to said phase inverter and responsive to afirst control signal to selectively apply either said azimuth signal orsaid elevation signal to said phase inverter, said phase inverte r beingresponsive to a second control signal to selectively impart a 180 phaseshift to the selectively applied azimuth or elevation signal; and addermeans coupled to said phase inverter and responsive to said sum signalandthe selectively phase-inverted signal derived from said phaseinverter and adapted to develop said microwave error signal therefrom.

2. In an electronic lobe switching system for locating a target in spaceand including a monopulse antenna having three output terminals whichprovide respectively a sum signal, an azimuth signal and an elevationsignal, a receiver responsive to a microwave error signal'and a'reference'signal and adapted todevelop corresponding demodulated errorvoltages therefrom, and a switching circuit responsive to said sumsignal, said azimuth signal and said elevation signal and adapted todevelop therefrom said microwave error signal, said switching circuitcoupling said monopulse I antenna to said receiver and comprising: aphase inverter; an electronic reference generator adapted to developsaid reference signal, a first control signal and elevation signal tosaid phase inverter, said phase inverter being coupled to said generatorand being responsive to said second control signal to sequentiallyimpart a 180 degree phase shift to the selectively applied azimuth orelevation signal; and adder means coupled to said phase inverter andresponsive to said sum signal and the sequentially phase-inverted signalderived from said phase inverter and adapted to develop said microwaveerror signal therefrom.

3. An electronic lobe switching system for locating a target in spacecomprising: a simultaneous lobing antenna including four symmetricallypositioned radiators defining the comers of a square, and hybridjunction means having four input terminals, a sum output terminal, anazimuth output terminal and an elevation output terminal, each of saidradiators being coupled to one of said input terminals and adapted toexcite a microwave signal therein representative of a microwave signalreceived from said target, said hybrid junction means being adapted todevelop a sum signal in said sum terminal, an azimuth signal in saidazimuth terminal and an elevation signal in said elevation terminalrepresentative of the range, the azimuth and the elevation of saidtarget respectively; a receiver responsive to a microwave error signaland a reference signal and adapted to develop demodulated error voltagesrepresentative of the azimuth and elevation of said target; and aswitching circuit coupling said simultaneous lobing antenna to saidreceiver, said switching circuit including a phase inverter; a microwavetwo-channel switch coupled to said phase inverter'and responsive to afirst control signal to selectively apply either said azimuth signal orsaid elevation signal to said phase inverter, said phase inverter beingresponsive to a second control signal to selectively impart a 180 phaseshift to the selectively applied azimuth or elevation signal, and addermeans coupled to said phase inverter and responsive to said sum signaland the selectively phase-inverted signal derived from said phaseinverter and adapted to develop said microwave error signal therefrom. II

4. An electronic lobe switching system for locating a target in spacecomprising: a simultaneous lobing antenna including four symmetricallypositioned radiators defining the corners of a square, and hybridjunction means having four input terminals, a sum output terminal, anazimuth output terminal and an elevation output terminal, each of saidradiators being coupled to one of said input terminals and adapted toexcite a microwave signal therein representative of microwave signalreceived from said target, said hybrid junction means being adapted todevelop a sum signal in said sum terminal, an azimuth signal in saidazimuth terminal and an elevation signal in said elevation terminalrepresentative of the range, the azimuth and the elevation of saidtarget respectively; a receiver responsive to a microwave error signaland a reference signal and adapted to develop demodulated error voltagesrepresentative of the azimuth and elevation of said target; and aswitching circuit coupling said simultaneous lobing antenna to saidreceiver, said switching circuit including a phase inverter, anelectronic reference generator adapted to develop said reference signal,a first control signal and a second control signal, a microwavetwo-channel switch coupled to said phase inverter and to said generatorand responsive to said first control signal to sequentially apply eithersaid azimuth signal or said elevation signal to said phase inverter,said phase inverter being coupled to said generator and being responsiveto said second control signal to sequentially impart a 180 degree phaseshift to the sequentially applied azimuth or elevation signal, and addermeans coupled to said phase inverter and responsive to said sum signaland the sequentially phase-inverted signal derived from said phaseinverter and adapted to develop said microwave error signal therefrom.

5. An electronic lobe switching system for locating a target in spacecomprising: a simultaneous lobing antenna including four symmetricallypositioned radiators defining the corners of a square, and a pluralityof intercoupled hybrid junctions having four input terminals, a sumoutput terminal, an azimuth output terminal and an elevation outputterminal, each of said radiators being coupled to one of said inputterminals and adapted to excite a microwave signal thereinrepresentative of a microwave signal received from said target, saidplurality of hybrid junctions being adapted to develop a sum signal insaid sum terminal, an azimuth signal in said azimuth terminal and anelevation signal in said elevation terminal representative of the range,the azimuth and the elevation of said target respectively; a receiverresponsive to a microwave error signal and a reference signal andadapted to develop demodulated error voltages representative of theazimuth and elevation of said target; and a switching circuit responsiveto said sum signal, said azimuth signal and said elevation signal andcoupling said simultaneous lobing antenna to said receiver, saidswitching circuit being adapted to develop said microwave error signaland including a microwave twochannel switch, a microwave phase inverter,and adder means, said switch being coupled to said phase inverter andresponsive to a first control signal for sequentially applying eithersaid azimuth signal or said elevation signal to said phase inverter,said phase inverter being responsive to a second control signal forsequentially introducing a 180 phase shift to the sequentially appliedazimuth or elevation signal, and adder means coupling said phaseinverter to said sum terminal and being adapted to mix the sequentiallyphase-inverted signal from said phase inverter and said sum signal todevelop said microwave error signal.

6. An electronic lobe switching system for locating a target in spacecomprising: a simultaneous lobing antenna including four symmetricallypositioned radiators defining the corners of a square, and a pluralityof intercoupled hybrid junctions having four input terminals, a sumoutput terminal, an azimuth output terminal and an elevation outputterminal, each of said radiators being coupled to one of said inputterminals and adapted to excite a microwave signal thereinrepresentative of a microwave signal received from said target, saidplurality of hybrid junctions being adapted to develop a sum signal insaid sum terminal, an azimuth signal in said azimuth terminal and anelevation signal in said elevation terminal representative of the range,the azimuth and the elevation of said target respectively; a receiverresponsive to a microwave error signal and a reference signal andadapted to develop demodulated error voltages representative oftheazimuth and elevation of said target; and a switching circuitresponsive to said sum signal, said azimuth signal and said elevationsignal and coupling said simultaneous lobing antenna to said receiver,said switching circuit being adapted to develop said microwave errorsignal and including a microwave twochannel switch, a microwave phaseinverter, adder means, and an electronic reference generator fordeveloping said reference signal and first and second control signals,said switch being coupled to said phase inverter and to said generatorand responsive to said first control signal for sequentially applyingeither said azimuth signal or said elevation signal to said phaseinverter, said phase inverter being coupled to said generator and beingresponsive to said second control signal for sequentially introducing aphase shift to the sequentially applied azimuth or elevation signal, andadder means coupling said phase inverter to said sum terminal and beingadapted to mix the sequentially phase-inverted signal from said phaseinverter and said sum signal to develop said microwave error signal.

7. An electronic lobe switching system for locating a target in spacecomprising: a simultaneous lobing antenna including four symmetricallypositioned radiators defining the corners of a square, and a pluralityof intercoupled hybrid junctions having four input terminals, a sumoutput terminal, an azimuth output terminal and an elevation outputterminal, each'of said radiators being coupled to one of said inputterminals and adapted to excite a microwave signal thereinrepresentative of a microwave signal received from said target, saidplurality of hybrid junctions being adapted to develop a sum signal insaid sum terminal, an azimuth signal in said azimuth terminal and anelevation signal in said elevation terminal representative of the range,the azimuth and the elevation of said target respectively; and aswitching circuit responsive to said sum signal, said azimuth signal andsaid elevation signal coupled to said simultaneous lobing antenna, saidswitching circuit being adapted to develop a microwave error signal andincluding a microwave two-channel switch, a microwave phase inverter andadder means, said switch being coupled to said phase inverter andresponsive to a first control signal for sequentially applying eithersaid azimuth signal or said elevation signal to said phase inverter,said phase inverter being responsive to a second control signal forsequentially introducing a 180 phase shift to the sequentially appliedazimuth or elevation signal, and adder means coupling said phaseinverter to said sum terminal and being adapted to mix the sequentiallyphase-inverted signal from said phase inverter and said sum signal todevelop said microwave error signal.

8. An electronic lobe switching system for locating a target in spacecomprising: a simultaneous lobing an tenna including four symmetricallypositioned radiators defining the comers of a square, and a plurality ofintercoupled hybrid junctions having four input terminals, a sum outputterminal, an azimuth output terminal and an elevation output terminal,each of said radiators being coupled to one of said input terminals andadapted to excite a microwave signal therein representative of amicrowave signal received from said target, said plurality of hybridjunctions being adapted to develop a sum signal in said sum terminal, anazimuth signal in said azimuth terminal and an elevation signal in saidelevation terminal representative of the range, the azimuth and theelevation of said target respectively; and a switching circuitresponsive to said sum signal, said azimuth signal and said elevationsignal coupled to said simultaneous lobing antenna, said switchingcircuit being adapted to develop a microwave error signal and includinga microwave two-channel switch, a microwave phase inverter, adder means,and an electronic reference generator for developing a reference signaland first and second control signals, said switch being coupled to saidphase inverter and to said generator and responsive to said firstcontrol signal

1. In an electronic lobe switching system for locating a target in space and including a monopulse antenna having three output terminals Which provide respectively a sum signal, an azimuth signal and an elevation signal, a receiver responsive to a microwave error signal and a reference signal and adapted to develop corresponding demodulated error voltages therefrom, and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal and adapted to develop therefrom said microwave error signal, said switching circuit coupling said monopulse antenna to said receiver and comprising: a phase inverter; a microwave two-channel switch coupled to said phase inverter and responsive to a first control signal to selectively apply either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being responsive to a second control signal to selectively impart a 180* phase shift to the selectively applied azimuth or elevation signal; and adder means coupled to said phase inverter and responsive to said sum signal and the selectively phase-inverted signal derived from said phase inverter and adapted to develop said microwave error signal therefrom.
 1. In an electronic lobe switching system for locating a target in space and including a monopulse antenna having three output terminals Which provide respectively a sum signal, an azimuth signal and an elevation signal, a receiver responsive to a microwave error signal and a reference signal and adapted to develop corresponding demodulated error voltages therefrom, and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal and adapted to develop therefrom said microwave error signal, said switching circuit coupling said monopulse antenna to said receiver and comprising: a phase inverter; a microwave two-channel switch coupled to said phase inverter and responsive to a first control signal to selectively apply either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being responsive to a second control signal to selectively impart a 180* phase shift to the selectively applied azimuth or elevation signal; and adder means coupled to said phase inverter and responsive to said sum signal and the selectively phase-inverted signal derived from said phase inverter and adapted to develop said microwave error signal therefrom.
 2. In an electronic lobe switching system for locating a target in space and including a monopulse antenna having three output terminals which provide respectively a sum signal, an azimuth signal and an elevation signal, a receiver responsive to a microwave error signal and a reference signal and adapted to develop corresponding demodulated error voltages therefrom, and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal and adapted to develop therefrom said microwave error signal, said switching circuit coupling said monopulse antenna to said receiver and comprising: a phase inverter; an electronic reference generator adapted to develop said reference signal, a first control signal and a second control signal; a microwave two-channel switch coupled to said phase inverter and to said generator and responsive to said first control signal to selectively apply either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being coupled to said generator and being responsive to said second control signal to sequentially impart a 180 degree phase shift to the selectively applied azimuth or elevation signal; and adder means coupled to said phase inverter and responsive to said sum signal and the sequentially phase-inverted signal derived from said phase inverter and adapted to develop said microwave error signal therefrom.
 3. An electronic lobe switching system for locating a target in space comprising: a simultaneous lobing antenna including four symmetrically positioned radiators defining the corners of a square, and hybrid junction means having four input terminals, a sum output terminal, an azimuth output terminal and an elevation output terminal, each of said radiators being coupled to one of said input terminals and adapted to excite a microwave signal therein representative of a microwave signal received from said target, said hybrid junction means being adapted to develop a sum signal in said sum terminal, an azimuth signal in said azimuth terminal and an elevation signal in said elevation terminal representative of the range, the azimuth and the elevation of said target respectively; a receiver responsive to a microwave error signal and a reference signal and adapted to develop demodulated error voltages representative of the azimuth and elevation of said target; and a switching circuit coupling said simultaneous lobing antenna to said receiver, said switching circuit including a phase inverter; a microwave two-channel switch coupled to said phase inverter and responsive to a first control signal to selectively apply either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being responsive to a second control signal to selectively impart a 180* phase shift to the selectively applied azimuth or elevation signal, and adder means coupled to said phase inverter and responsive to saId sum signal and the selectively phase-inverted signal derived from said phase inverter and adapted to develop said microwave error signal therefrom.
 4. An electronic lobe switching system for locating a target in space comprising: a simultaneous lobing antenna including four symmetrically positioned radiators defining the corners of a square, and hybrid junction means having four input terminals, a sum output terminal, an azimuth output terminal and an elevation output terminal, each of said radiators being coupled to one of said input terminals and adapted to excite a microwave signal therein representative of a microwave signal received from said target, said hybrid junction means being adapted to develop a sum signal in said sum terminal, an azimuth signal in said azimuth terminal and an elevation signal in said elevation terminal representative of the range, the azimuth and the elevation of said target respectively; a receiver responsive to a microwave error signal and a reference signal and adapted to develop demodulated error voltages representative of the azimuth and elevation of said target; and a switching circuit coupling said simultaneous lobing antenna to said receiver, said switching circuit including a phase inverter, an electronic reference generator adapted to develop said reference signal, a first control signal and a second control signal, a microwave two-channel switch coupled to said phase inverter and to said generator and responsive to said first control signal to sequentially apply either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being coupled to said generator and being responsive to said second control signal to sequentially impart a 180 degree phase shift to the sequentially applied azimuth or elevation signal, and adder means coupled to said phase inverter and responsive to said sum signal and the sequentially phase-inverted signal derived from said phase inverter and adapted to develop said microwave error signal therefrom.
 5. An electronic lobe switching system for locating a target in space comprising: a simultaneous lobing antenna including four symmetrically positioned radiators defining the corners of a square, and a plurality of intercoupled hybrid junctions having four input terminals, a sum output terminal, an azimuth output terminal and an elevation output terminal, each of said radiators being coupled to one of said input terminals and adapted to excite a microwave signal therein representative of a microwave signal received from said target, said plurality of hybrid junctions being adapted to develop a sum signal in said sum terminal, an azimuth signal in said azimuth terminal and an elevation signal in said elevation terminal representative of the range, the azimuth and the elevation of said target respectively; a receiver responsive to a microwave error signal and a reference signal and adapted to develop demodulated error voltages representative of the azimuth and elevation of said target; and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal and coupling said simultaneous lobing antenna to said receiver, said switching circuit being adapted to develop said microwave error signal and including a microwave two-channel switch, a microwave phase inverter, and adder means, said switch being coupled to said phase inverter and responsive to a first control signal for sequentially applying either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being responsive to a second control signal for sequentially introducing a 180* phase shift to the sequentially applied azimuth or elevation signal, and adder means coupling said phase inverter to said sum terminal and being adapted to mix the sequentially phase-inverted signal from said phase inverter and said sum signal to develop said microwave error signal.
 7. An electronic lobe switching system for locating a target in space comprising: a simultaneous lobing antenna including four symmetrically positioned radiators defining the corners of a square, and a plurality of intercoupled hybrid junctions having four input terminals, a sum output terminal, an azimuth output terminal and an elevation output terminal, each of said radiators being coupled to one of said input terminals and adapted to excite a microwave signal therein representative of a microwave signal received from said target, said plurality of hybrid junctions being adapted to develop a sum signal in said sum terminal, an azimuth signal in said azimuth terminal and an elevation signal in said elevation terminal representative of the range, the azimuth and the elevation of said target respectively; and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal coupled to said simultaneous lobing antenna, said switching circuit being adapted to develop a microwave error signal and including a microwave two-channel switch, a microwave phase inverter and adder means, said switch being coupled to said phase inverter and responsive to a first control signal for sequentially applying either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being responsive to a second control signal for sequentially introducing a 180* phase shift to the sequentially applied azimuth or elevation signal, and adder means coupling said phase inverter to said sum terminal and being adapted to mix the sequentially phase-inverted signal from said phase inverter and said sum signal to develop said microwave error signal.
 8. An electronic lobe switching system for locating a target in space comprising: a simultaneous lobing antenna including four symmetrically positioned radiators defining the corners of a square, and a plurality of intercoupled hybrid junctions having four input terminals, a sum output terminal, an azimuth outpuT terminal and an elevation output terminal, each of said radiators being coupled to one of said input terminals and adapted to excite a microwave signal therein representative of a microwave signal received from said target, said plurality of hybrid junctions being adapted to develop a sum signal in said sum terminal, an azimuth signal in said azimuth terminal and an elevation signal in said elevation terminal representative of the range, the azimuth and the elevation of said target respectively; and a switching circuit responsive to said sum signal, said azimuth signal and said elevation signal coupled to said simultaneous lobing antenna, said switching circuit being adapted to develop a microwave error signal and including a microwave two-channel switch, a microwave phase inverter, adder means, and an electronic reference generator for developing a reference signal and first and second control signals, said switch being coupled to said phase inverter and to said generator and responsive to said first control signal for sequentially applying either said azimuth signal or said elevation signal to said phase inverter, said phase inverter being coupled to said generator and being responsive to said second control signal for sequentially introducing a 180 degree phase shift to the sequentially applied azimuth or elevation signal, and adder means coupling said phase inverter to said sum terminal and adapted to mix the sequentially phase-inverted signal from said phase inverter and said sum signal to develop said microwave error signal. 